It is a bit more difficult than that, as a considerable proportion of artists do have/do need a day job (even when their formal education and academic grades are in the field of arts) - going by the incomes registered with the KSV (German artists social insurance) the vast majority are in the powerty range, with an income between the minimum 4,000 and 12,000€ a year.
Arguably this is a bit less so in photography - if any, photography is a day job complement for many artists. But all writers I know have some other primary source of income (often not that far off their books, in teaching or journalism), and musicians and actors don't fare much better.